1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2015 Oracle. All rights reserved.
5 * Support for backward direction RPCs on RPC/RDMA (server-side).
8 #include <linux/module.h>
9 #include <linux/sunrpc/svc_rdma.h>
10 #include "xprt_rdma.h"
12 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
14 #undef SVCRDMA_BACKCHANNEL_DEBUG
17 * svc_rdma_handle_bc_reply - Process incoming backchannel reply
18 * @xprt: controlling backchannel transport
19 * @rdma_resp: pointer to incoming transport header
20 * @rcvbuf: XDR buffer into which to decode the reply
23 * %0 if @rcvbuf is filled in, xprt_complete_rqst called,
24 * %-EAGAIN if server should call ->recvfrom again.
26 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
27 struct xdr_buf *rcvbuf)
29 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
30 struct kvec *dst, *src = &rcvbuf->head[0];
39 p = (__be32 *)src->iov_base;
43 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
44 pr_info("%s: xid=%08x, length=%zu\n",
45 __func__, be32_to_cpu(xid), len);
46 pr_info("%s: RPC/RDMA: %*ph\n",
47 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp);
48 pr_info("%s: RPC: %*ph\n",
49 __func__, (int)len, p);
53 if (src->iov_len < 24)
56 spin_lock(&xprt->recv_lock);
57 req = xprt_lookup_rqst(xprt, xid);
61 dst = &req->rq_private_buf.head[0];
62 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
63 if (dst->iov_len < len)
65 memcpy(dst->iov_base, p, len);
67 credits = be32_to_cpup(rdma_resp + 2);
69 credits = 1; /* don't deadlock */
70 else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
71 credits = r_xprt->rx_buf.rb_bc_max_requests;
73 spin_lock_bh(&xprt->transport_lock);
75 xprt->cwnd = credits << RPC_CWNDSHIFT;
76 if (xprt->cwnd > cwnd)
77 xprt_release_rqst_cong(req->rq_task);
78 spin_unlock_bh(&xprt->transport_lock);
82 xprt_complete_rqst(req->rq_task, rcvbuf->len);
86 spin_unlock(&xprt->recv_lock);
91 dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
96 dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
97 xprt, be32_to_cpu(xid));
102 /* Send a backwards direction RPC call.
104 * Caller holds the connection's mutex and has already marshaled
105 * the RPC/RDMA request.
107 * This is similar to svc_rdma_send_reply_msg, but takes a struct
108 * rpc_rqst instead, does not support chunks, and avoids blocking
111 * XXX: There is still an opportunity to block in svc_rdma_send()
112 * if there are no SQ entries to post the Send. This may occur if
113 * the adapter has a small maximum SQ depth.
115 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
116 struct rpc_rqst *rqst)
118 struct svc_rdma_op_ctxt *ctxt;
121 ctxt = svc_rdma_get_context(rdma);
123 /* rpcrdma_bc_send_request builds the transport header and
124 * the backchannel RPC message in the same buffer. Thus only
125 * one SGE is needed to send both.
127 ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer,
128 rqst->rq_snd_buf.len);
132 ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
136 ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0);
141 dprintk("svcrdma: %s returns %d\n", __func__, ret);
145 svc_rdma_unmap_dma(ctxt);
146 svc_rdma_put_context(ctxt, 1);
151 /* Server-side transport endpoint wants a whole page for its send
152 * buffer. The client RPC code constructs the RPC header in this
153 * buffer before it invokes ->send_request.
156 xprt_rdma_bc_allocate(struct rpc_task *task)
158 struct rpc_rqst *rqst = task->tk_rqstp;
159 size_t size = rqst->rq_callsize;
162 if (size > PAGE_SIZE) {
163 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
168 /* svc_rdma_sendto releases this page */
169 page = alloc_page(RPCRDMA_DEF_GFP);
172 rqst->rq_buffer = page_address(page);
174 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
175 if (!rqst->rq_rbuffer) {
183 xprt_rdma_bc_free(struct rpc_task *task)
185 struct rpc_rqst *rqst = task->tk_rqstp;
187 kfree(rqst->rq_rbuffer);
191 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
193 struct rpc_xprt *xprt = rqst->rq_xprt;
194 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
198 /* Space in the send buffer for an RPC/RDMA header is reserved
199 * via xprt->tsh_size.
203 *p++ = rpcrdma_version;
204 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
210 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
211 pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
214 rc = svc_rdma_bc_sendto(rdma, rqst);
216 goto drop_connection;
220 dprintk("svcrdma: failed to send bc call\n");
221 xprt_disconnect_done(xprt);
225 /* Send an RPC call on the passive end of a transport
229 xprt_rdma_bc_send_request(struct rpc_task *task)
231 struct rpc_rqst *rqst = task->tk_rqstp;
232 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
233 struct svcxprt_rdma *rdma;
236 dprintk("svcrdma: sending bc call with xid: %08x\n",
237 be32_to_cpu(rqst->rq_xid));
239 if (!mutex_trylock(&sxprt->xpt_mutex)) {
240 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
241 if (!mutex_trylock(&sxprt->xpt_mutex))
243 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
247 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
248 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
249 ret = rpcrdma_bc_send_request(rdma, rqst);
251 mutex_unlock(&sxprt->xpt_mutex);
259 xprt_rdma_bc_close(struct rpc_xprt *xprt)
261 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
265 xprt_rdma_bc_put(struct rpc_xprt *xprt)
267 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
270 module_put(THIS_MODULE);
273 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
274 .reserve_xprt = xprt_reserve_xprt_cong,
275 .release_xprt = xprt_release_xprt_cong,
276 .alloc_slot = xprt_alloc_slot,
277 .release_request = xprt_release_rqst_cong,
278 .buf_alloc = xprt_rdma_bc_allocate,
279 .buf_free = xprt_rdma_bc_free,
280 .send_request = xprt_rdma_bc_send_request,
281 .set_retrans_timeout = xprt_set_retrans_timeout_def,
282 .close = xprt_rdma_bc_close,
283 .destroy = xprt_rdma_bc_put,
284 .print_stats = xprt_rdma_print_stats
287 static const struct rpc_timeout xprt_rdma_bc_timeout = {
288 .to_initval = 60 * HZ,
289 .to_maxval = 60 * HZ,
292 /* It shouldn't matter if the number of backchannel session slots
293 * doesn't match the number of RPC/RDMA credits. That just means
294 * one or the other will have extra slots that aren't used.
296 static struct rpc_xprt *
297 xprt_setup_rdma_bc(struct xprt_create *args)
299 struct rpc_xprt *xprt;
300 struct rpcrdma_xprt *new_xprt;
302 if (args->addrlen > sizeof(xprt->addr)) {
303 dprintk("RPC: %s: address too large\n", __func__);
304 return ERR_PTR(-EBADF);
307 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
308 RPCRDMA_MAX_BC_REQUESTS,
309 RPCRDMA_MAX_BC_REQUESTS);
311 dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
313 return ERR_PTR(-ENOMEM);
316 xprt->timeout = &xprt_rdma_bc_timeout;
317 xprt_set_bound(xprt);
318 xprt_set_connected(xprt);
319 xprt->bind_timeout = RPCRDMA_BIND_TO;
320 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
321 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
323 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
324 xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
325 xprt->ops = &xprt_rdma_bc_procs;
327 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
328 xprt->addrlen = args->addrlen;
329 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
332 xprt->max_payload = xprt_rdma_max_inline_read;
334 new_xprt = rpcx_to_rdmax(xprt);
335 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
338 args->bc_xprt->xpt_bc_xprt = xprt;
339 xprt->bc_xprt = args->bc_xprt;
341 if (!try_module_get(THIS_MODULE))
344 /* Final put for backchannel xprt is in __svc_rdma_free */
349 xprt_rdma_free_addresses(xprt);
350 args->bc_xprt->xpt_bc_xprt = NULL;
351 args->bc_xprt->xpt_bc_xps = NULL;
354 return ERR_PTR(-EINVAL);
357 struct xprt_class xprt_rdma_bc = {
358 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
359 .name = "rdma backchannel",
360 .owner = THIS_MODULE,
361 .ident = XPRT_TRANSPORT_BC_RDMA,
362 .setup = xprt_setup_rdma_bc,